This invention relates to SrTiO3 co-doped with a first trivalent metal dopant atom (e.g. yttrium) replacing some of the Sr atoms on a strontium sub-lattice in the A site of the molecule and a second pentavalent dopant metal atom(e.g. niobium) replacing some of the Ti atoms on a titanium sub-lattice in the B site of the molecule, and to solid oxide fuel cells including an anode made of the co-doped SrTiO3.
The solid oxide fuel cell (SOFC) is one of the most advanced systems for generating electricity in an efficient and environmentally friendly way. It can operate on a variety of fuels in addition to hydrogen, and may find applications from transportation to stationary systems (1, 2).
There has been a long history of research on the application of cermets (ceramic-metal composites) of nickel and yttria stabilized zirconia (YSZ) as anodes in solid oxide fuel cells. However, Ni—YSZ has a number of drawbacks including sintering of the Ni particles at high operating temperatures, sulfur poisoning and carbon deposition when the SOFC is fuelled by natural gas, reliance on a triple phase junction for the electrochemical reaction and cost. Ni—YSZ cermet anodes cannot be used in pure methane without pre-reforming. Therefore, an alternative material with adequate conductivity (>50-100 S/cm at 800-1000° C.) and catalytic activity toward total or partial oxidation of methane is necessary. Mixed ionic-electronic conductor (MIEC) oxides, either perovskite type (3-5) or non-perovskite (6-9) type, exhibiting high ionic and electronic conductivities at elevated temperatures are attractive candidates for SOFC electrodes. Mixed conductors are believed to relax the limitation attributed to electronic conducting electrodes by expanding the active reaction zone to include the whole of the electrode-gas interface instead of so-called triple phase boundary area (10).